The irreducible factorisation of 3a³ + 6a is
(a) 3a (a² + 2)
(b) 3 (a³ + 2)
(c) a (3a² + 6)
(d) 3 × a × a × a + 2 × 3 × a

Solution:

The correct answer is (a), because

From the given expression 3a³ + 6a taking ‘3a’ as a common factor we get 3a (a² + 2). Further we may notice that the term (a² + 2) is not having any term common and not factorable further.

✦ Try This: The irreducible factorisation of 2b³ + 8b is (a) 2b(b² + 2), (b) 2(b² + 2), (c) 2b(b² + 4), (d) 2 × b × b × b + 2 × 4 × b

The correct answer is (c), because

From the given expression 2b³ + 8b taking ‘2b’ as a common factor we get 2b (b² + 4).

Further, we may notice that the term (b² + 4) is not having any term common and not factorable further.

☛ Also Check: NCERT Solutions for Class 8 Maths Chapter 9

NCERT Exemplar Class 8 Maths Chapter 7 Sample Problem 3

The irreducible factorisation of 3a³ + 6a is (a)3a (a² + 2), (b) 3 (a³ + 2), (c) a (3a² + 6), (d) 3 × a × a × a + 2 × 3 × a

Summary:

The irreducible factorisation of 3a³ + 6a is 3a (a² + 2)

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